1. Technical Field of the Invention
The present invention relates to an apparatus for determining the number of microorganisms in air, with a device for the settlement of microorganisms, said device having a lower part and a cover, a nutrient or culture medium being located in the interior of the settlement device and to a method for operating this apparatus.
2. Prior Art
To detect the number of microorganisms, in particular germs, such as fungae, bacteria, etc., in air, it is known to cause germs suspended in the air to settle on a culture medium during a predetermined timespan. This culture medium is then covered and exposed to conditions which are conducive to the reproduction of the settled germs. After a predetermined timespan has elapsed, seats or zones on the culture medium which result from the growth of the settled germs are counted.
A so-called Petri dish, which has a lower part with a nutrient medium as well as a cover, is used for carrying out this method. The cover is removed from the lower part and the Petri dish is left open during a desired timespan. The Petri dish is then closed again by hand. The accuracy of this way of measuring the number of germs in air depends largely on the carefulness of the person who carries out these measurements manually. Moreover, this previously known method makes it necessary for the person carrying out such measurements to be present during the entire measuring operation. This is unfavorable, in particular, when such measurements have to be carried out outside the usual work time, in a place where access is difficult, etc.